"We can confirm that the B sample analysis of a sample collected from Mr. Gay has been completed and that the B sample analysis has confirmed the A sample findings," USADA CEO Travis Tygart said in a statement.

Tygart also said an additional sample collected from the American sprinter had also returned "an adverse A sample finding."

A tearful Gay said in an interview on July 14 that his A sample from the out-of-competition test in May had returned a positive result for a substance he would not disclose.

The 2007 world double sprint champion then asked the B sample be tested. He has withdrawn from the US team for next month's world championships in Moscow.